Screw and screw driver

ABSTRACT

A screw and complementary screw driver for use in relatively inaccessible places where, with conventional tools, difficulty would be encountered in locating the screw on end of screw driver in axial alignment therewith. Screw driver has a generally V-shaped screw engaging means having a root portion extending from screw driver stem, and a transverse portion interconnecting root portion with an oblique portion, the oblique portion extending obliquely to transverse portion. Screw has bridge portion with clearance passage extending under bridge portion to accept the V-shaped means, passage having clearance at inner and outer ends for insertion and removal of screw driver. Stop member is threaded onto outer end of oblique portion to draw screw driver into axial alignment with screw and to maintain screw on end of screw driver for all inclinations of screw driver.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to complementary engaging means of a screw andscrew driver particularly adapted for use in awkward or relativelyinaccessible locations where a common screw and screw driver would beinconvenient.

2. Prior Art

There is a long standing problem relating to applying torque to screwsin awkward or relatively inaccessible places where the screw cannot beheld temporarily by hand whilst being rotated prior to "biting" orengaging the opening into which it is being screwed. Heads of commonscrews are provided with engaging means to engage complementary screwdriver bits, for example the slot head, Phillips or Robertson engagingmeans. However, none of these engaging means positively hold the screwon the screw driver so that the screw is maintained in axial alignmentwith the screw driver when the screw driver is held at any inclinationto the horizontal. Furthermore, when torque is applied by the screw insome of the common engaging means, reaction forces are generated betweenthe engaging means which tend to disengage the engaging means, thuscausing the screw driver to slip relative to the screw.

SUMMARY OF THE INVENTION

The invention reduces the difficulties and disadvantages of the priorart by providing complementary engaging means of a screw and a screwdriver in which the screw is held positively and releasably on the screwengaging means of the screw driver and in axial alignment therewith topermit complete control of the screw before and during engagement withthe opening into which it is to be screwed, for all angular dispositionsof the screw driver.

The screw engaging means of the invention extends from a shank of thescrew driver and is generally V-shaped and includes a root portion, atransverse portion and an oblique portion. The root portion extends fromthe shank to join the transverse portion. The transverse portioninterconnects the root and oblique portions, and the oblique portionextends obliquely from the transverse portion. The screw of theinvention has a threaded body and screw head, the screw head havingdriver engaging means characterized by a bridge portion adjacent anouter portion of the screw head remoted from the body. A clearancepassage extends under the bridge portion to accept the V-shaped screwengaging means, the passage having clearance at either end thereof forinsertion and removal of the V-shaped screw engaging means.

A detailed disclosure following, related to drawings, describes apreferred embodiment of the invention which is capable of expression instructure other than that particularly described and illustrated.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified fragmented section of a first embodiment of ascrew and screw driver according to the invention, shown mutuallyengaged,

FIG. 2 is a simplified top plan view of the screw and screw driver ofFIG. 1, a stop member being omitted,

FIG. 3 is a simplified fragmented section on Line 3--3 of FIG. 1,

FIG. 4 is a simplified fragmented section of a second embodiment of ascrew and screw driver according to the invention,

FIG. 5 is a simplified fragmented section of Line 5--5 of FIG. 4,

FIG. 6 is a simplified fragmented section of a third embodiment of ascrew and screw driver according to the invention,

FIG. 7 is a simplified fragmented top plan of the screw and screw driverof FIG. 6, some portions being omitted.

DETAILED DISCLOSURE FIGS. 1 through 3

A screw 10 according to the invention has a cylindrical screw head 11and a threaded body 12 disposed on a central axis 14 of the screw. Ascrew driver 16 according to the invention has a shank 17 and agenerally V-shaped screw engaging means 18 extending from an end of theshank. The screw engaging means has a root portion 20, a transverseportion 21 and an oblique portion 22. The root portion extends from theshank 17 and the transverse portion interconnects the root and obliqueportions. The oblique portion extends obliquely from the transverseportion 21 so as to define the general V-shape of the screw engagingmeans. For convenience of definition, the oblique portion is consideredto be bent or inclined at an acute angle 25 to the transverse portion.The angle 25 is typically 45 degrees, but depending upon requirementsthe angle can be within a range defined by a relatively shallow angle27, of about 30 degrees, and a relatively steep angle 28 of about 60degrees. The transverse portion 21 is relatively short and has an axis30 which is disposed generally normally to the axis 14 of the screw.Alternatively the angle of inclination of the oblique portion can bedefined with reference to the screw driver shank, and thus can be withina similar range of inclination of between 30 degrees and 60 degrees tothe shank.

The screw engaging means 18 can be a separable "bit" and be releasablyconnected to the screw driver shank 17 by a releasable connecting means31 which forms no portion of the invention. The connecting means can becommon complementary male and female portions of the shank and screwengaging "bit" which are retained in engagement by a spring means (notshown). The oblique portion 22 has a threaded outer end 32 and carries acylindrical stop member 34, (not shown in FIG. 2) the stop member havingan internal thread means to permit threading onto the end 32 to retainthe screw on the screw driver as will be described.

The screw head 11 has a driver engaging means 33 characterized by abridge portion 36 adjacent an outer surface 35 of the screw head remotedfrom the body. The bridge has a bridge axis 37 coincident with a chordof the screw head so as to be displaced from a diameter 38 of the screwhead, and spaced opposed bridge inner and outer side walls 42 and 43.The wall 42 is parallel to and is displaced from the diameter 38 of thescrew head by an amount 44 which is sufficient to permit the screwengaging means 18 to be retained in the driver engaging means 33 withthe shank 17 of the screw driver aligned with the central axis 14 of thescrew. It can be seen that the amount 44 is generally equal to one halfof lateral width or diameter 46 of the root portion 20 which is adjacentthe bridge portion when the screw driver engages the screw The rootportion is shown to be cylindrical at the plane of section but forincreased stength changes to a square cross-section adjacent thetransverse portion.

The means 33 includes a clearance passage 39 extending under the bridgeportion to accept the screw engaging means 18 as shown in FIG. 1, thepassage having inner and outer ends 40 and 41 respectively. The innerand outer ends 40 and 41 are spaced sufficiently from the bridge portionto provide clearance at either end of the passage sufficient forinsertion and removal of the screw engaging means 18, which is shown inbroken outline at 18.1 in a partially inserted position. Note that thestop member 34 is removed for such insertion or removal.

The clearance passage 39 has a central axis 48 disposed generallyradially of the screw head and generally coincident with the axis 30 ofthe transverse portion 21. The passage 39 is further defined in part byan undersurface 50 of the bridge portion, a pair of spaced passage sidewalls 52 and 53, and a passage inner surface 55 disposed oppositely tothe undersurface 50 of the bridge portion. The passage side wall 52 and53 are spaced equally from the central axis 48 of the passage and aregenerally normal to the bridge axis 37. As best seen in FIG. 3, when thescrew engaging means 18 engages the screw, opposite sides 58 and 59 ofthe transverse portion 21 are adjacent the passage side walls 52 and 53respectively. The sides 58 and 59 are complementary to the side walls 52and 53 respectively so that torque applied to the screw driver by anoperator is transmitted from the screw engaging means 18 to the means ofthe screw head mainly through the passage side walls and thecomplementary opposite sides of the transverse portion. The oblique androot portions have similarly undesignated opposite sides, whichsimilarly engage adjacent complementary portions of the passage totransmit torque to the screw.

The clearance at the inner end 40 of the passage is defined in part by apassage inner end wall 61 which is disposed on a side of the screwremote from the bridge portion so as to provide sufficient clearance forinsertion of the oblique and transverse portions under the bridge aspreviously described and shown in broken outline at 18.1 in FIG. 1. Theclearance at the outer end 41 of the passage is provided by theclearance passage extending to break through a cylindrical periphery 64and rim 65 of the screw head. Thus the passage extends through an openside of the screw head and thus such a screw would not be used in acounterbored or counter-sunk hole as there would be insufficientclearance for the oblique portion to project from the screw. Alternativescrews suitable for counter-sunk holes are shown in FIGS. 4 and 6. It isnoted that an inner end face 63 of the stop member 34 bears against therim 65 of the screw head. This is to maintain suitable engagement andalignment of the complementary engaging means during application oftorque, and also to prevent the screw driver accidentally disengagingfrom the screw head.

The bridge portion 36 has an outer surface 66 that is generally flushwith the outer surface 35 of the screw head, and the passage innersurface 55 is disposed inwardly of a surrounding portion of the outersurface 35. Thus the driver engaging means 33 in the screw head isessentially flush with the outer surface 35 of the screw head.

OPERATION

If the screw is to be inserted in a vertical wall or roof surface or ina relatively awkward location, the screw can be releasably secured onthe end of the screw driver in axial alignment therewith by insertingthe screw engaging means through the clearance passage 39 until thethreaded outer end 32 projects above the outer surface 35 of the head.The stop member 34 is screwed onto the end 32 until the inner face 63bears on the rim 65 and then further rotation of the member 34 draws theroot portion 20 generally laterally against the bridge inner side wall42 so as to maintain the shank 17 of the screw driver in alignment withthe screw axis 14. The screw is then positively located on the screwdriver and can be inserted at any inclination into the hole in thenormal manner and the screw driver is then rotated to screw inwards intothe hole. When the screw is sufficiently imbedded, the stop member 34 isunscrewed and the screw engaging means disengaged by reversing the aboveprocedure.

If the space around the screw is restricted it is of advantage toseparate the screw engaging means 18 from the screw driver shank at thereleasable connection 31. This permits easy engagement with, ordisengagement from, the screw without the need of excessive clearancearound the screw that would otherwise be required if the bit were notseparable from the shank. If the screw engaging means is permanentlysecured to the shank of the screw driver, some considerable clearance isrequired around the screw to permit swinging of the screw driver aboutthe screw through approximately 90 degrees to permit insertion andengagement of the screw engaging means. Clearly for correct operationthe screw engaging means is inserted only in the inner end of theclearance passage.

ALTERNATIVES AND EQUIVALENTS FIGS. 4 and 5

An alternative screw head 72 has an outer surface 73 and an axis 74. Thehead has an alternative driver engaging means 71 having an alternativebridge portion 75 having an outer surface 76 disposed outwardly of theouter surface 73. The screw head has a truncated conical periphery 78and thus is a counter-sunk head screw, which permits recessing of thehead in a complementary counter-sunk hole. Alternative screw engagingmeans 80 of a screw driver (not shown) has similar root, transverse andoblique portions 81, 82 and 83 respectively and, whilst this screwengaging means is basically similar to the means 18 of FIG. 1, it isnoted that the transverse portion is extended somewhat thus increasingarea of contact between side walls of the transverse portion and thescrew head.

A clearance passage 85 extends under the bridge portion 75 and has innerand outer ends 86 and 87 for insertion and removal of the screw engagingmeans 80, and an inner surface 88 disposed inwardly of the surroundingportion of the outer surface 73 of the screw. It is noted that the outerend 87 of the clearance passage breaks through the outer surface 73 ofthe screw head 72 and is clear of the periphery 78 of the head and thusis suitable for use with the counter-sunk screw, because the obliqueportion does not interfere with the side wall of the complementary holeinto which the screw head fits. The screw engaging means has a threadedouter end 89 to accept a threaded stop member 90. The member 90 has aninner rim 91 which interferes with the upper surface 73 of the head whenthe stop member is screwed tightly onto the oblique portion 83 thusdrawing the root portion 81 against the bridge 75.

The bridge portion 75 has an undersurface 93 generally level with theouter surface 73 of the screw. Thus it can be seen the bridge has adepth 95 projecting outwards from the surface 73. An alternative bridgeportion 75.1, shown in broken outline in FIG. 5 only, projects furtherfrom the surface 73 and has an under surface 93.1 disposed outwardly ofthe surface 73, thus providing additional clearance for insertion of theengaging means.

In operation, the alternative complementary engaging means 71 and 80function similarly to equivalent structure previously described withreference to FIGS. 1 through 3.

FIGS. 6 and 7

A second alternative counter-sunk screw head 101 has a screw axis 102and a similar truncated conical periphery 103. The screw head has agenerally flat outer surface 104 and an alternative driver engagingmeans 100 having a bridge portion 106 with an outer surface 107generally flush with the surface 104. In contrast with the previouslydescribed screw head, the bridge has an axis 105 which coincides with adiameter 108 of the screw head, and has spaced opposed bridge inner andouter side walls 109 and 110 respectively spaced equally on oppositesides of the diameter as shown.

The means 100 has a clearance passage 112 in the screw head extendingunder the bridge portion to inner and outer ends 113 and 114 which areclear of the periphery 103. An alternative screw engaging means 116 hasroot, transverse and oblique portions 118, 119 and 120 respectivelywhich are generally similar to equivalent portions of the previouslydescribed screw engaging means. The root portion extends from aninclined end portion 122 of a screw driver shank 123 to accommodate thediametrically disposed bridge portion 106 so that when the engagingmeans 100 and 116 are engaged, the screw driver shank 123 is alignedwith the screw axis 102. The inclined end portion 122 thus displacestransversely from the shank the root portion, together with thetransverse and oblique portions of the engaging means to ensurealignment when torque is applied to the screw. A threaded stop member121 can be threaded onto the end of the oblique portion 120 andtightening of the stop member draws the root portion 118 against theinner side wall 109 of the bridge portion thus preventing disengagementand maintaining alignment as aforesaid.

It is seen that the alternative means 100 has a symmetrically disposedbridge portion and, with suitable design, the inner and outer ends 113and 114 of the clearance passages can be disposed symmetrically aboutthe bridge portion 107 permitting insertion of the screw engaging meansfrom either side of the bridge portion. Such an arrangement eliminatesthe difficulty of inserting the screw engaging means in the previouslydescribed embodiments which are assymmetrical and in which the obliqueportion must clearly be inserted always from a side adjacent the innerbridge side wall. Clearly the screw drivers of FIGS. 1 and 4 cannot beused effectively with the screw head 101 of FIG. 6 and vice versa.

I claim:
 1. A screw for use with a screw driver; the screw driver havinga shank and a generally V-shaped screw engaging means at an end of theshank, the screw engaging means having a root portion, a transverseportion and an oblique portion, the root portion extending from theshank as an axial extension of the shank to join the transverse portion,the transverse portion interconnecting the root and oblique portions,and the oblique portion extending obliquely from the transverse portionso as to define the generally V-shaped screw engaging means; the screwhaving a threaded body and a screw head disposed on a central axis ofthe screw, the screw head having an outer surface, and a driver engagingmeans characterized by:(a) a bridge portion adjacent the outer surfaceof the screw head remote from the body, the bridge portion having abridge axis coincident with a chord of the screw head being displacedradially outwardly from a diameter of the screw head with the entirebridge portion being located to one side of said diameter, the bridgeportion also having spaced opposed bridge inner and outer side walls,the bridge inner side wall being parallel to and radially displaced fromsaid diameter of the screw head an amount sufficient to permit the screwengaging means of the screw driver to be retained in the screw with theshank of the screw driver aligned with the central axis of the screw,(b) a clearance passage extending under the bridge portion to accept theV-shaped screw engaging means, the passage having clearance at inner andouter ends thereof for insertion and removal of the V-shaped engagingmeans.
 2. A screw as claimed in claim 1 in which:(a) the bridge innerside wall is displaced an amount generally equal to one-half of lateralwidth of the root portion of the screw engaging means which is adjacentthe bridge portion when the screw driver engages the screw.
 3. A screwas claimed in claim 1 in which the clearance passage has a central axisdisposed generally radially of the screw head and is further defined inpart by:(a) an under surface of the bridge portion, (b) a pair of spacedpassage side walls spaced equally from the central axis of the clearancepassage, the central axis of the passage being generally normal to thebridge axis, (c) a passage inner surface disposed oppositely to theunder surface of the bridge portion, and clearance at the inner end isdefined in part by: (d) a passage inner end wall disposed on a side ofthe screw remote from the bridge portion, so that when the screwengaging means engages the driver engaging means of the screw, portionsof the spaced passage side walls are adjacent opposite sides of thetransverse portion of the screw engaging means so as to transmit torquefrom the screw engaging means to the screw.
 4. A screw as claimed inclaim 1 in which:(a) the bridge portion has an outer surface that isgenerally flush with the outer surface of the head of the screw head. 5.A screw as claimed in claim 1 in which:(a) the bridge portion has anouter surface disposed outwardly of the outer surface of the head of thescrew, (b) the passage inner surface is disposed inwardly of asurrounding portion of the outer surface of the screw.
 6. A screw asclaimed in claim 1 in which:(a) the screw head is cylindrical and has acylindrical periphery and rim, (b) the clearance passage extends throughthe screw head to break through the cylindrical periphery and rim.
 7. Ascrew as claimed in claim 1 in which:(a) the screw head is a countersunkscrew head and has a truncated conical periphery, (b) the outer end ofthe clearance passage breaks through the outer surface of the screw headand is clear of the periphery of the screw head.